Bearing arrangements are known for both thrust bearing arrangements and journal bearing arrangements. It is convenient to discuss one type only, say thrust bearing arrangements, knowing that comparable points relate to the other type
Tilting pad thrust bearing arrangements are well known per se for supporting such a rotatable shaft subject to forces along the axis of rotation by having an axially facing collar, affixed to the shaft, bear against axially facing thrust bearing pads which in turn bear against a supporting carrier member and relative to which they can tilt to alter the relationship between the bearing surfaces of the pads and the shaft borne collar surface.
The supporting carrier is formed either as a metal ring of such thickness as to support the thrust loads without deformation or sometimes as a prepared surface of the apparatus housing the bearing arrangement. In either case it is conventional, but not mandatory, for the pad-supporting face of the carrier to be substantially planar, except possibly for lubricant nozzles at the surface at locations between adjacent pads, and for the face of each thrust pad opposite to a bearing surface to bear on the carrier over an area smaller than the area of the pad face, effectively defining a fulcrum ridge or shoulder at the surface of one or both by way of which the pad is supported on said supporting face of the carrier and about which pivot or ridge it is able to make limited tilting movements The pad and/or carrier face may be machined away other than at a central or circumferentially offset location to leave a radially-extending pivot or fulcrum ridge.
It is known from GB-A-2107001 to mount each bearing pad of the ring array with respect to the pad-supporting face of the carrier, against relative displacement in circumferential, radial and axial directions, by means of a pair of locating pins which extend at an angle to each other between respective locating holes in the pad and carrier, each pin being fixed with respect to one of the pad or carrier and a slack fit with respect to the other so as to allow the pad to pivot about its pivot/ridge with respect to the carrier. The pad is retained with respect to the carrier by virtue of abutment between the sides of the holes and the shanks of the pins. For preference, the locating pins lie in a plane passing through the pivotal axis of the pad, most conveniently at or near the opposite ends of the fulcrum ridge, the separation, divergence of pin axes and slack locating in one hole of the pair associated with each pin being such as to permit the pad and carrier to be located with respect to each other by manipulation involving movement in at least two directions that would not occur in use to permit accidental separation.
It is, however, a relatively complex manipulation to locate and remove individual bearing pads of the ring assembly and has to be performed manually by practised personnel.
It is also known to locate such a bearing pad by means of conventional headed screws which extend parallel to each other in a generally axial direction through clearance holes in the carrier into threaded engagement with holes in the bearing pad, the clearance with respect to the carrier being both radially with respect to the shank of each screw and also axially with respect to its head to permit the limited tilting of the pad and screws relative to the carrier. The use of such threaded screws does of course introduce additional manufacturing steps in provided threaded and countersunk clearance holes, as well as requiring locking means to prevent them coming loose.
Similar considerations apply in respect of mounting pads of journal bearings, in respect of locating them against displacement from a carrier that in use surrounds and is radially disposed with respect to a shaft.
There is a class of bearing implementation where cost is an overriding factor. Bearings assemblies of carrier and tilting pads for such uses typically operate for the life of the apparatus to which fitted or, if less, entail the whole bearing being replaced rather than disassembled for replacement of individual pads, the assembly of bearing carrier and pads being discarded by the user.
In such a throw-away environment it becomes important to be able to manufacture and install the bearing arrangement simply and at low cost. It is also important with regard to recent and forthcoming waste disposal legislation that such a bearing be manufactured with as few different materials as possible and readily broken apart to permit final disposal or re-cycling.
Thus one of the principal requirements is for the discrete pads and carrier to be manufactured individually and pre-assembled cheaply before use. This includes operations to be performed in manufacturing the component parts themselves and in the skill and time required for assembly. It follows that such pre-assembly must result in a product that is stable insofar as it can be transported, handled and manipulated for installation (or removal) without disturbing the relationship between pads and carrier.